Thrips preferences and host suitability - factors in the transmission of tomato spotted wilt tospovirus by the western flower thrips.

摘要

The tomato spotted wilt tospovirus (TSWV) has seriously affected production of commercial crops worldwide. While the pathogen can only be transmitted by the thrips, the larva is the only stage that can acquire the virus from a diseased plant. Thus, the western flower thrips (WFT), Frankliniella occidentalis (Pergande), one of the more important vectors of TSWV, need to develop on the virus hosts to be able to spread and perpetuate the disease cycle. Despite extensive TSWV hosts in the Hawaiian agrosystems, there is paucity of information on their importance as reservoir hosts of WFT. This study focused on elucidating the virus-vector-host plant relationships.; Host preferences by adult thrips generally determine the host where eggs will be laid and larvae would subsequently develop. At the vegetative stage, romaine lettuce, Lactuca sativa v. longifolia, was found the most preferred host by WFT for oviposition. However, a shift of thrips preferences to flowering weeds indicated their role as alternate sources of WFT at this plant phenological stage.; The suitability of plant hosts for WFT development differed among species at four rearing temperatures when evaluated with a growth index, female reproductive potential and biotic increase of thrips populations. Romaine lettuce and cheese weed, Malva palviflora, were the most suitable hosts particularly at warmer temperatures, while jimson weed, Datura stramonium, and burdock, Arctium lappa, supported growth of WFT at cooler temperatures. Findings indicated that these plant species are potential thrips hosts during summer or winter and spring periods. Foliar golden crown-beard, Verbesina enceloides, was unsuitable for WFT development hence, less important in the epidemiology of TSWV.; Thrips transmission of TSWV demonstrated that infection occurs from the weeds to crop species through primary spread; that secondary infection takes place between plants of a crop species; and, that romaine lettuce emerges as the most important crop source of TSWV and WFT that can effect virus spread to weeds and other plant crops by emigration of viruliferous adults.; This study resulted in a clearer understanding of the virus-vector-host plant interrelationships. Based on the host attributes determined for the different plant species, better management strategies can be formulated and recommended to mitigate the impact of tomato spotted wilt tospovirus disease.